When selecting a LED replacement bulb for your recessed light fixture, you will need to be familiar with the designations of various styles, and sizes, of bulbs. BR means the bulb will have a Bulged Reflector lens; this is the most common type of bulb used in recessed lighting. PAR is short for Parabolic Aluminized Reflector, this type of bulb will have a flat lens (which may be an important aesthetic consideration), and is designed to provide maximum output of light. The number following either BR or PAR, such as 30 or 40, refers to the diameter of the lens in 1/8 inch increments. Therefore, a BR30 bulb will be 30 times 1/8", which totals 3.75" in width, and a PAR40 bulb will be 5" in width. Now you are ready to light up your ceiling fixtures with money saving LED bulbs!